Monday, June 02, 2008

Oleophilic nanowires

Researchers led by Francesco Stellacci at the Massachusetts Institute of Technology in Cambridge, US, made membranes of tangled manganese oxide nanowires around 50 micrometres thick – about a quarter of the thickness of normal office paper.

The tiny wires are first suspended in liquid, before being strained out into flat sheets. "It's very similar to the process that makes paper," Stellacci says.

The manganese oxide nanowires are normally very attractive to water. However, adding a silicon coating switches the material to being strongly water repellent. It also becomes able to guzzle oil. Tests showed the material can suck up 20 times its weight in motor oil, and 10 times its weight in gasoline.

"Our material can be left in water a month or two, and when you take it out it's still dry," Stellacci says. "But if that water contains some hydrophobic [oily] contaminants they will get absorbed."

But Lahann points out that manganese oxide may not be the best material for real-world applications because it could be toxic. He says, though, that the new material "clearly provides a blueprint that can guide the design of future nanomaterials for environmental applications."------------